Friction brake



March 28, 1939. c. c. FARMER '2,151,844

y FRICTION BRAKE Filed April 17, 195e 2 sheets-swat l 4a 45,44 a? aa 24 a INVENTOR CLYDE. C. FAHME H ATTORN EY 4 Poicniojd I2s, 193e I".

artists PATENr caries iriuc'rion Baena c'lydc c. Former; Pittsburgh, Po., signor to VThe Westinghouse. Air

Brake (iompany,` will unending, Pa., a' corporation. oi.' Pennsylvania Application Apr-ll 1v, 1936, s criioi No. 'sassi' i 18 Claims. (Ci. 18S-153) invention relates to brake apparatus and more particularly to thattype oi' apparatus disclosed in my pending application, Serial No. 74,830

iled April 11,1936, which isoperative in effecting 5 anapplication oi' the brakes to iirst move a brake element such as a'brake shoe into engagement with a member to'be braked such as a rotatable A brake drum and to then apply braking pressure 2 to the brake element, saidapparatus comprising a mechanism. for moving the brake element into engagement with the brake drum and also comprises an expansible n letal tube which cooperates with saldmechanism to apply vbraking `pressure to the brake element upon the admission of uid i l5 under pressure thereto. Y

' One object oi the ,invention is--to'prgyide an improved brake apparatus *of the above meri-- tioned type having means for preventing the expansible metal tubeironr being vcrushed when the tubeisinits normal contracted condition and lthc mechanism for movin.;` the brake y:excluent into engagement with the brake drum tends to exert pressure on the tube'.-

:Another ohicctl oi-ihc invention is to;V providey an improved brake apparatus of the above men-- tioned type with means whereby a single expancible tubular metal diaphragm is employed iol scltnt'rolvthe braiing force on a plurality oi' brake 1 l cov vAnouar obicccortheinvoniion ic-io'provlde an improved clasp brake apparatus having brake shoes disposed at opposite sides ofa rotatable brake drumor other membertobebraked. which A shoes are movable into with themember to be braked by meansof iiuid pressure responsive mcchcnian and which are adopted iof bc forced into braking engagement with -the-Jmember to be raked bymeans ci an -expanslhie tubular metal diaphragm which is not-permitted to func; 40 tionuntil the-iluid pressure responsive mecha- 'o nisln functions tomove th b o e mn lever is operatively connected, .by means o! a'pin tact wlththe member.

l noihcr objects and. advantages `in the following mol-c dctaueddescripuou or invention.

elevational viewoi' a brake apparatus embodying theinvention, 'portions "of the apparatus broken away and portions being shown in section to more clearly illustrate the invention; Fig. 2 is a vertical sectional lview taken on the line 2-2 of Fig. 1; Fig. 3 is a side elevational view o f the Xapparatus, portions'of the mechanism for l ss voperating' the brake shoes being shown in section:

member.' lo

-' 'As shown, the motori comprises a motor frame 4to which is secured a housing member 5 having a bearing portion 6 in which the armature shaft 2 is journalled. f The shaft 2 extends'outwardly -a short distance beyond the bearing portion 6 15` and at its end has secured theretothe brake The apparatus comprises arcuate brake shoes 'I and 8, the shoe 1, in the present embodiment of the 4inver ition,being arranged at the upper side of 20 the brake 'drum I and the shoe 8 being'arranged at the lower side of the drum.. Each ofthe brake shoes is bodily movable in a vertical plane in I directions toward and away from the brake'drunn' the upper brake shoe 1 being slidably guided at -25V each end by a stationary lug' 9 preferably integral .with the housing member 5 and the shoe 8 being slidably guided at each end by a similar stationary lug I0.- The lugs 9. and I0, besides guiding the --shoes as they are moved toward and away from 30 the brake drum also serve to prevent the shoes, 'when-in -contact .with1the drunL-from. izieingA moved in the direction of rotation of the drum.

At each side of the brakedrum and between Athe ends or tho-bnlrcshoes 'l` and s is a short 35'.

transversely extending lever il which, atits inner end, is rockably mounted on'a pin i2 secured to the housing member l-'and which at its outer' end is operatively connected to the lower end of a short substantlally'vertically disposed pullrod Il by' 40 means of a pinilf Intermediate its ends this upwardly from the adjacent end of the brake shoe v s cnd'whi'ch as shown may be intesraiwiilrthef Intheaccompanyincdrawinssnr. iis e shoe" 'rnc upper end ofihc pull rod l; 'is pivoicuy` I9 which may be integra1 withthe brake shoe 1v.- The inner end of the lever I8 is provided with an upwardly directed extension 20 which is operativelyf'engaged-'by a pressure exerting mechanism .n hereinafter more rully described. ila

Interposed between each end of the brake shoe 1 and the adjacent lever I3 and operatively en- Saging both the lever and the shoe is a release spring 2| which at all times tends to move the shoe and lever toward their release position.

The pressure exerting mechanism-above referred to may comprise a tubular expansible metallic diaphragm 22 which, in the present embodiment of the invention, is shown folded to provide three expansible layers .which are separated by two vertically movable follower plates 23. The upper layer of the diaphragm is in engagement with an outwardly extending flange 24 of the member and the bottom layer is in operative engagement with the upper face of a wedge member 25 which is in operative engagement with a wedge member 26 which is movable lin the direction of its length relative to the wedge member 25. The upwardly directed extensions 20 of the levers I8 are maintained in operative engagement with the lower surface of the wedge member 26 by the action of the release springs 2| and when the wedge member 26 is moved `toward the right hand in the direction of its length, the wedge member 25 cooperating therewith moves it downwardly causing the inner ends of both leversk I8 to move downwardly as will hereinafter more fully appear.

The right hand end of the wedge member 25 abuts against a vertically disposed outwardly extending flange 21 of the housing 5 and is provided with an outwardly extending stop lug 28 which is received in a' vertically' extending groove 29 formed inthe flange. The rear face of the wedge member is provided with a similar stoplug 30 which is received ina vertically extending groove 3| formed in the adjacent portion of the housing 5. The upper ends of the grooves are closed to form stop shoulders which shoulders with the brake released, engage the lugs and thereby limit upward movement of the wedge member. By limiting the upward movement of the wedge member the possibilty of crushing the diaphragm 4 22 in its contracted state when, as will hereinafter be fully described, the wedge mechanism moves the brake shoesinto contact with brakedrum I prior to the admisson of fluid under pressure to the diaphragm.

'Ihe operation of the wedge adapted to be effected by means of a. cylinder mechanism which is located at one end of the wedge and which comprises a cylinder `32 rigidly secured to the housing 5. operatively mounted in the cylinder is a piston 33 having a stem 34 which extends through an opening in the non-pressure head of the cylinder into operative engagement with one end of thevwedge member 26, `the wedge gember being slidable on the end of the piston At one side of the piston. is a chamber 35 which is connected through a passage 35 `to an application andV release passage and vpipe 31.

The open end of the diaphragm 22 is connected through a exible tube 38 and pipe and passage I6 to a chamber 48 provided in the cylinder casing said chamber containing a piston yalve 4I which in adapted to control communication between chamber 43 and a chamber 42 at the other side of the valve piston which is connected through a passage 43` to the piston'chanilier 35, said valve piston being normally held closed, as

shown in Fig. 1, by the action of a coil spring 44.

' The valve piston 'chamber 48 is connected through a unidirectional flow passage 45 to the application and release passage 31. v there being;

n l I member 26 is.

movement of the parts in the opposite direction being prevented by the rear wall ofthe housing.

The brake drum I may be of any desired construction but as shown in the drawings preferably comprises a spoked wheel having a plurality of radially arranged spaced cooling fins 48 extending inwardly from the rim of the wheel.

When it is desired to effect an application of 'the brakes, fluid under pressure is supplied to the application and release passage and pipe 31 from any desired source. Fluid under pressure flows from the passage 31 through passage 36 to the piston chamber 35 and-causes the piston 33 and its stem 34 to move outwardly. Since the stem 34 is in operative engagement with the wedge member 26, the piston will cause the member to move toward the right. As the wedge member 26 is thus moved the wedge member 25 is maintained against movement in the same direction by the engagement of the right hand end of the member by the flange 21 of the housing 5 and vertical movement of the wedge member 25 is prevented by the engagement of the shoulders at the ends of the grooves 29 and 3| engaging the stop lugs 28 and 30, respectively, of the wedge member. Since the wedge member 25 cannot be moved upwardly the wedge member 26, as it moves longitudinally, is caused to move downwardly. It will here be noted that since the wedge member cannot be moved upwardly from its normal position the diaphragm when fully contracted cannot be crushed when, in initiating an application of the brakes, the piston 33 operates to cause the brake shoes to move into contact with the brake drum. v

The wedge 26 as it is thus moved downwardly exerts pressure on the inner ends of the levers I8 causing them to rock about their pivotal connections with the brake shoe 1. Each lever as it is thus rocked, movesthe pull rod connected'to the outer end thereof upwardly, causing the lever II connected to the rod to rock in the same direction about the pin I2, 'both levers II as they are thus operated causing .the brake shoe 1 to be moved toward the brake drum I. At the same time as the brake shoe 1 is being moved toward the brake drum the levers I8 rock on the pins I1 causing the brake shoe 1 to be moved toward the brake drum I.

At the time the braking surfaces of the brake shoes come in contact with the braking surface of the brake drum, the pressure of fluid in chamber 42 will have been increased suiiiclently to cause the valve 4I to move upwardly from its seat against the opposing pressure of the spring 44 so that fluid under pressure now flows from the application and release passage 31 to the diaphragm 22 by way of passage 36, piston chamber 35, passage 43, chamber 42, past the unseated valve 4I, through valve chamber 48, passage 33 and flexible tube 33.

Fluidunder pressure thus supplied to the dia- Dhragm 22 causes each ofy the several layers thereof to expand andi apply braking force to the brake shoes through the medium of the wedges 25 nism from moving to collapse said tube when the and 2s and the mechanisms associated therewith and the brake shoes. I 1 To release the brakes the application and release pipe 31 is connected to the atmosphere and seat the piston valve 4 I the now of iluid from the diaphragm 22`wi11 continue by way of passage 45, past the ball check valve 46 to the passage and pipe 31. 1

Now` when the pressure of uid in piston chamber 35 has been reduced to some lowl degrec, a spring 50 lwhich is connected at one end to the wedge member 26 and at the other end to the cylinder casing 32, acts to move the wedge member 26 toward the left to its release position, said wedge /member being in engagement with the piston stem 34, causing the piston 33 to be moved to its normal position as lshown in Fig. 1.

As the wedge member 26 is thus moved, the release springs 2l act to cause the brake shoes l and 8 to be moved out of contact with the brake,

drum and act through the brake shoe 1, levers Il, pull rods I3,'and levers I8 to cause the wedge member to moveupwardly to thereby remain in operative engagement with the wedge member 25.

While one. illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims. Y

'Having now described by invention,` what I claim as new and desire to secure by Letters Patent. is:-

1. In a fluid pressure brake apparatus, in com-- aination, a rotatable member to be braked, .a :rake element adapted to engage said member, a stationary housing,mechanism operative in initiating an application of the brakes for moving .said 'element into engagement with said member, an expansible metal tube adapted to be expanded by duid underpressure alter the application of the rakes is initiated ionapplying braking force to said mechanism and thereby to said element when the` element is in engagement' with said nember, means operative automatically in initiiting the application` of the brakes for admitting luid under pressure to said metal tube and neans included intsaid mechanism adapted to coperate with 'said housing for preventing they ransmission of pressure from s aid mechanism 'o said tube when the mechanism is operated.- 2. In'a uid pressure brake apparatus, in comoination, a rotatable member to ,be braked, a

:rake element adapted to engage said memben: a. housing, mechanism'carried by said housing perative in initiating an application of the' brakes For moving said element' into. engagement with ier pressure afterntherapplicatlcn off-.the brakes; aas been initiated. to.' apply braking pressuregto' and element when the'eiement is Vin engagement' with said'membenstop'shoulders on said housing,

indstop lugs on said mechanism adaptedto enzageiv'vith said shoulders l'to' prevent`- the .mecha-A mechanism is operated to move said element into engagement with said member.

3. In a huid pressure brake apparatus, in combination, a rotatable member to be braked, a

brake element adaptedto ensasesaid member, a

stationary housing, mechanism including two cooperating wedge members operative in eiiecting anv application of the brakes for moving said element into engagement with said member, a iuid pressure responsive expansible tube associated with said wedge members, means-on one of said wedge'members adapted to cooperate with l said housing for preventing said mechanism from collapsing said tube when the mechanism is operated to move said element into engagement with said member. and means operativeautomatically after said mechanism has been set in operation to eilect the expansion of said tube to apply braking pressure -to said element. 4. In a iluid pressure brake apparatus, incombination, a` rotatable member to be braked, a

brake element adapted to engage said member, a

stationary housing, mechanism canied by said housing and operative in eii'ectingan application of the brakes for movingvsaid element into en- Y gagement with said member. a'tube mounted in .said-housing and associated with said mechanism and normally connected to the atmosphere and adapted to be expanded by uid under pressure to apply said element with pressure to said member, means for delaying the supply of uid under pressure tosaid tube while said mechanism is operating to move said clement into engagement with said member, and means included in'said` mechanism and cocperating with said housing for preventing said mechanism, as it is operated. from collapsing said tube. l

5. In a uid pressure brake, in combination, a rotatablemember to be braked, -a brake element-, normally spaced away from said member 'and movable into engagement therewith. a stationary housing, mechanism including means cooperating with said housing and operative by fluid under pressure supplied ,thereto for moving said element into engagement with said member, and a metal tubel associated with said mechanism and cooperating with said housing adapted to be expanded'to apply pressure to said element only when the pressure of iluid supplied to said mechanism is suiiicient'undernormal operating conditions to cause the mechanism to operate to move said 'element into engagement with said' member, said means also cooperating with said housing for preventing said tube from being collapsed when saidmechanism'is operating tomove grd element 'into engagement with said mem- 6: In a clasp brake apparatus, in-combination,

sets o f operatively connected levers for simultaneously moving said brake shoes in opposite direc,-A

Y said two sets of mechanisms, to movezthe brake a rotatable member Ito be braked, two brake shoes: arranged one at. each side of said member, two

shoes in engagement with said member, an expansible hollow diaphragm cooperating with said means and operable by iluid under pressure to apply' said shoes with pressure to said member, and means preventing the fluid pressureoperated means, when being actuated, frcm exerting presst u'e on said diaphragm.

7. In a clasp brake apparatus. in combination,

rotatable member to be braked, two brake shoes ione at. each side of said member, two

sets of operatively connected levers for simultaneou'sly moving said brake shoes in opposite directions into engagement with said member, means operative by fluid under pressure for actuating said two sets of mechanisms, to move the brake shoes in engagement with said member, an expansible metal tube cooperating with said means and operable by fluid under pressure to apply said shoes with pressure to said member, and means for preventing the uid pressure operated means when being actuated from exerting pressure on said diaphragm.

8. In a clasp brake apparatus. in combination, a rotatable member to be braked, two brake shoes arranged one at each side of said member. two sets of 'operatively connected levers for simultaneously moving said brake shoes in opposite dlrections into engagement with said member to thereby take up slack in the apparatus, means operative by iluid under pressure `:for actuating said two sets of levers to move the brake shoes to take up the slack in the apparatus, other means operative by iluid under pressure for applying braking pressure to the rlrst mentioned means and thereby to said two sets of leversA and brake` shoes, and means preventing the ilrst mentioned fluid pressure operated means from exerting pressure on said other means when the first mentioned fluid pressure operated means is beingoperated to move said shoes to take up slack.

9. In a clasp brake apparatus, in combination, a rotatable member to be braked, two brake shoes arranged one at each side of said member, two

sets of operatively connected levers for simultalevers without exerting pressure on said metal' tube.

10. In a clasp brake apparatus, in combination, a rotatable member to be braked, two brake shoes arranged one at each side of said member, two sets of operatively connected levers for simultaneously moving said brake shoes in opposite directions into engagement with said member to thereby take up slack in the apparatus, means operative by fluid under pressure for actuating said two sets of levers to move the brake shoes to take up the slackin the apparatus, ametal tube adapted to be expanded by fluid under pressure for applying braking pressure to said means and thereby to said levers and brake shoes, valve means for delaying the supply 0f iluid under pressure to said tube until the pressure of uid supplied to said means is suillcient under normal conditions to cause the operation of the means.

and means for preventing said means 'in effecting' the operation of said sets of levers from exerting pressure on said tube. Y

1l. In a fluid pressure brake, in combination, a rotatable member to be braked, a brake element adapted to engage said member, mechanism operative in effecting. an application of the brakes mechanism .adapted to be eipanded to apply braking pressure to said mechanism and thereby to said element when under normal operating conditions the slack between said element and member is. taken, up.

4 13. In a fluid pressure brake, in combination, a rotatable member to be braked, a brake element adapted -to engage saidmember, a stationary housing, mechanism carried by said housing operative in effecting an application of thebrakea to move said element into engagement with said member, mechanically expansible means cooperating with said housing and mechanism for actuating said mechanism, fluid pressure expansible means cooperating with said housing for applying pressure to said mechanically expansible means'and thereby to said mechanism and element when, under normal operating conditions, the slack between said element and member has been taken up, and means for preventing said mechanical expansibie means from exerting pressure on said fluid pressure expansible means prior to the operation of the uid pressurev expansible means.

14. In a iluid pressure brake, in combination, a rotatable member to be braked, a brake element adapted ,to engage said member, a. stationary housing, mechanism carried by said housing operative'in effecting an application of the brakes to move said element into engagement with said member, mechanically expansible means carried by said housing for actuating said mechanism, :duid pressure expansible means carried by said housing forapplying pressure to said mechanically expansible means and'thereby to said mechanism and element when, under normal operating conditions, the slack between said element and member has been taken up, and means f or preventing the force of the mechanically expansible means when being expanded from being transmitted to said fluid pressure expansible means.

l5. In a fluid pressure brake apparatus, in combination, a rotatable member to be braked, a brake element adapted to engage said member, a stationary housing, mechanism operative in applying the brake for rst moving said brake element into engagement with said member, means including an expansible tube which is then expanded by iiuid under pressure to apply pressure through said mechanism to -said element, and means included in said mechanism adapted to engage said housing `for preventing the transmission to said tube of pressure exerted by the initial operation of said mechanism.

16. In a fluid pressure brake apparatus, in combination, a rotatable member to be braked, a brake element adapted to engage vsaid member, an ez-pansible tube adapted to bev expanded by iluid under pressure to apply pressure to said element, a mechanism having a member interposed between said tube and` said element and operative to move said element relatively to said tube into engagement with said rotatable member, and means'for preventing the transmission tc said tube of pressure exerted by the operation of said mechanism.

17. In a clasp brake apparatus, in combina n, a. casing, a rotatable member to be braked, t o brake shoes arranged one at each side of d member, two sets of operatively connected le ers for moving said shoes in opposite-directions into engagement with said member, each of said sets of levers comprising alever iulcrumed intermediate its ends on one of said shoes. a level fulcrumed at one end to said casing and operatively connected intermediate its ends to the other of said shoes, a rod operatively connecting outer ends of said "levers, means operative for actuating the levers fulcrumed to the brake shoe for moving the brake shoes to take up slack between the shoes and the member, and uid pressure expansible means for exerting braking torce onsaid mechanically expansible means and thereby on said sets of levers.

` ate its ends mechanically expansible member, two sets of operatively connected levers for moving said shoes in opposite directions into engagement with said member, each of said sets of levers comprising a lever fulcrumed intermedion one of said shoes. a. lever tull crumed at one end to said casing and operatively connected intermediate its ends to the other of said shoes, a rod operatively connecting outer ends ot said levers, mechanically expansble means operative foi-.actuating the levers full0 crumed to the brake shoefor moving the brake 

